A positron emission tomography (PET) apparatus has been known as a nuclear medical imaging apparatus that can perform functional diagnosis in living tissue of subjects.
In imaging by the PET apparatus, for example, first, a subject is administered with a radioactive pharmaceutical labeled with a positron emission nuclide. The positron emission nuclide selectively captured into living tissue within the subject emits positrons, and the emitted positrons combine with electrons, undergo pair annihilation, and emit a pair of gamma rays in substantially opposite directions. The PET apparatus detects the gamma rays using detectors arranged around the subject in a ring shape and generates coincidence counting information (a coincidence list) from the detection result. The PET apparatus generates a PET image by reconstruction using the generated coincidence counting information.
The detector of the nuclear radical imaging apparatus such as the PET apparatus includes, for example, a scintillator and a photomultiplier. The scintillator converts a gamma ray emitted from internal tissue within a subject into light having a peak in the ultraviolet region and outputs the light. The photomultiplier converts the light output from the scintillator into an electric signal.
Recently detectors using a SiPM as the photomultiplier have practically been utilized. In such a detector, a SiPM is installed for each scintillator, and reading channel is assigned to each SiPM, thus leading to an enormous number of reading channels.